1. Field of the Invention
This invention relates to a process for the removal of printing inks from printed wastepaper in the presence of alkoxylates of blown oils as deinking chemicals. The invention also relates to the use of these special deinking chemicals for the removal of printing inks from printed wastepaper.
2. Discussion of Related Art
Today, wastepaper is used in large quantities for the production of, for example, newsprint and sanitary paper. Lightness and color are important quality features for papers of this type. To achieve this, the printing inks have to be removed from the printed wastepaper. This is normally done by deinking processes. These processes are carried out in conventional installations for the recycling of wastepaper which are equipped with additional facilities for removing the detached printing ink particles. Two important steps in the deinking process are:
(1) Disintegration of the wastepaper. Disintegration is the process in which the wastepaper is fiberized. It may be induced, for example, in aqueous medium by application of mechanical energy (stirring). Fiberizing is accompanied by detachment of the printing ink particles. The disintegration step gives a paper stock suspension in the form of a grey pulp. (2) Removal of the detached printing ink particles from the paper stock suspension. This step of the deinking process may be carried out by washing or flotation cf. for example Ullmanns Encyclopadie der technischen Chemie, 4th Edition, Vol. 17, pages 570 -571 (1979)!.
The deinking of wastepaper is normally carried out at alkaline pH values in the presence of alkali metal hydroxides, alkali metal silicates, oxidative bleaches and surfactants at temperatures in the range from 30.degree. to 50.degree. C. Anionic and/or nonionic surfactants, for example soaps, ethoxylated fatty alcohols and/or ethoxylated alkyl phenols, are mainly used as surfactants cf. for example "Wochenblatt fur Papierfabrikation" 17, 646 to 649 (1985)!.
German patent application DE 34 01 444 relates to a process for the deinking of wastepaper using a compound corresponding to the following general formula EQU RCOO--(CH.sub.2 CH.sub.2 O).sub.m --(AO).sub.n --R'
in which R is a C.sub.7-21 alkyl or alkenyl group, R' is a hydrogen atom or a C.sub.1-18 alkyl, alkenyl or acyl group, AO represents C.sub.3 H.sub.6 O or C.sub.4 H.sub.8 O groups or a mixture of C.sub.2 H.sub.4 O, C.sub.3 H.sub.6 O and C.sub.4 H.sub.8 O groups, m is an integer of 1 to 100 and n is an integer of 1 to 100.
The use of ethoxylated castor oils for the deinking of printed wastepaper is known from JP 78/52705, reported in Chem. Abstr. 89, 131445j (1978), and from DE 21 48 590. The Japanese patent describes mixtures of castor oil with 10 to 400% ethylene oxide and ethoxylated nonylphenol which are suitable for the removal of printing inks from printed wastepaper. The process protected in DE-PS 21 48 590 is concerned with organic materials, for example paper, which are bleached with sodium chlorite in the presence of organic compounds containing at least one ethylene oxide and/or propylene oxide unit. Suitable organic compounds containing at least one alkylene oxide unit include inter alia ethoxylated castor oil.